Thermal insulating container, method of manufacturing thereof and hermetic closing kit therewith

ABSTRACT

A thermal insulating container for containing substances and maintaining substances at a determined temperature is disclosed. The container has a continuous containment wall which extends in a single body and defines an inner containment region with an opening. The containment wall has a first, or outer layer, of ceramic material, and a second, or inner layer, facing towards the inner containment region of ceramic material and separated from the first layer forming a gap region inside which a vacuum is created. The outer layer has a hole for exit of the air during the step of firing the ceramic material and for extraction of air and creation of the vacuum inside the gap following the firing. The container also has closing means for hermetically closing the hole once the vacuum has been created.

TECHNICAL FIELD

The present invention relates to a thermal insulating container for containing one or more substances and maintaining the substances at a determined temperature. Additionally, the invention relates to a hermetic closing kit comprising said container and a closing element. Further, the invention relates to a method for realising said container.

PRIOR ART

With the aim of maintaining a substance thermally insulated from the external environment, containers are known that are made of glass, metal or plastic, in which the walls are formed by a double-layer defining a gap inside which an insulating material is inserted. In an effective way, especially in the scientific sector where high reliability is required in terms of thermal insulation, an absolute vacuum is created inside the gap.

With the presence of the vacuum, the heat cannot be conducted by conduction or convection and can be conducted only by radiation. Loss by radiation is usually minimised by applying a reflective cladding on the surfaces, such as for example a metal.

For practical uses, the container must have an opening in order to introduce the substance to be contained. Consequently, use of a closing element or a cap made of insulating material is necessary, usually made of plastic with the aim of preventing heat loss. However, the junction element between the cap and the container is one of the critical elements in loss of heat towards the outside.

As evidenced, the use of the vacuum inside the gap is used for obtaining highly efficient containers. However, not all the materials or configurations of materials have shown themselves to be suitable for supporting a vacuum-creating process and especially for maintaining the vacuum over time inside the gap.

For this reason thermal insulating containers for daily use are made of more economic materials and alternative procedures in the creation of the vacuum, for thermally insulating the substance contained. In detail, a partial vacuum is usually created in the gap, or an insulating material is inserted, such as for example gassy substances which limit the thermal conduction.

In the field of vessels in general, for example, usually materials such as plastic, glass and metal are used, or a combination thereof. However, it has been observed that these structures are subject to a high loss by radiation, especially at the edges thereof.

Ceramic can also be mentioned among the materials used in this field. However, ceramic is generally used only as a cladding for some parts of the container. Given the typical characteristics of some ceramic materials (hardness, a low degree of transpiration or absorption of substances, thermal resistance, etc.), there have been numerous attempts to realise containers of this type using only ceramic material. Unfortunately satisfactory results have not been achieved. In fact, the high-temperature ceramic firing processes make it indispensable to leave openings for preventing breakage of the walls of any gaps due to air expansion during the firing step. Therefore it is extremely complicated to realise a gap in a completely ceramic material in order to create the vacuum and maintain it internally thereof.

An object of the present invention is to overcome partially or fully the drawbacks mentioned above in relation to known thermal insulating containers and to provide a container that is more effective and functional.

DESCRIPTION OF THE INVENTION

A thermal insulating container is described herein, and a hermetic closing kit and a method for realising the container according to the independent claims.

The container according to the present invention is able to contain one or more substances and maintain the substances at a determined temperature. In particular, the container comprises a continuous containment wall which extends in a single body and defines an inner containment region with an opening, in which the containment wall has an edge portion in proximity of the opening.

Specifically, the containment wall is constituted by a first layer, or outer layer, of ceramic material, and a second layer, or inner layer, facing towards the inner containment region. The second layer is separated from the first layer so as to form a gap region wherein inside said gap the vacuum is created.

The outer layer advantageously comprises at least a hole for exit of the air during the step of firing the ceramic material and for extraction of the air and creation of the vacuum inside the gap following the firing step. The container further comprises closing means for hermetically closing the hole once the vacuum has been created.

According to the present invention, it is possible to realise containers of various sizes and shapes able to maintain the temperature of the contained substances practically constant. The container can for example assume the shape of a bottle, a glass, a plate, a cup, so as to conserve the contained substance hot or cold, while maintaining the external surface at ambient temperature. Naturally the container can also assume a shape such as to contain, in turn, another recipient. It would be possible, for example, to realise the container as a bottle holder or a glass holder, etc.

The thickness of the layers of the containment wall can be of a few millimetres, comprised between 1 millimetre and 6 millimetres, in particular about 2 or 3 millimetres.

For this reason, this container can be of a modest weight and can be easily transported. Therefore the container could be conformed in such a way as to make it suitable, for example, for transport of foodstuffs or other materials which must be maintained at a determined temperature. Specifically the container can assume the shape of a box or small trunk provided with suitable handles or shoulder-straps, easy to transport.

The container is advantageously made only of a ceramic material. Therefore standard moulding procedures can be used for realising any shape or dimension.

The resulting container can therefore be a generic “tableware” item, i.e. can be a dish, a plate, a cup, a glass, a bottle or a jug, which can be used for the enjoyment of foods and drinks with recipients designed to exalt the specific organoleptic and nutritional properties of the contents and preserve the temperature thereof when serving and dispensing.

The hole present on the outer layer is preferably used both to eliminate the air from the gap during the firing step, thus preventing the breaking of the ceramic surfaces, and to extract the air in order to create the vacuum once the firing has concluded. This can be obtained by inserting the container inside a vacuum chamber which sucks the air out through the hole. This can be advantageously realised in an assembly line system in which closing means can be applied to close the hole hermetically once the vacuum has been created. The closing means can for example be caps made of a polymeric material with silicone on the slots. The hole is usually made at the base of the container. However the hole can be made in any other position along the outer layer of the containment wall. Further, it is possible to realise a container provided with a plurality of said holes.

To obtain a better hermetic quality, a further cladding might be included, with ceramic material, and a consequent step of firing the zones of the containment wall closed with the closing means. Note that as a result of the presence of the vacuum inside the gap, an eventual re-firing of the walls does not lead to any risk of breakage as there is no gas present capable of expanding inside said gap.

Using hard feldspathic porcelain enables using the non-porous properties so as not to alter the organoleptic and nutritional qualities of the contained substance, and enables conferring resistance to pressure notwithstanding the internal vacuum.

In an embodiment of the present invention, the ceramic material is non-porous hard feldspathic porcelain.

Porcelain is an excellent material for preservation of the organoleptic properties of the substances contained. Further, thanks to the level of hardness of porcelain, differently to other materials, the continuous containment wall is able to withstand atmospheric pressure and any eventual impacts, although there is a vacuum inside the gap.

In particular, the porcelain used for the present invention comprises kaolin, feldspar and quartzes.

In a further embodiment of the invention, the ceramic material of the first and second layer is realised according a spongy reticulated structure similar to sponges, or nanospheres made of porcelain.

In an embodiment of the device according to the present invention, the first layer forms a continuous body with the second layer and is in direct contact with the second layer at least at the edge portion of the containment wall.

In this way a container having two layers can be obtained with a single firing process, determining an enormous advantage in terms of mass production.

In an alternative embodiment of the invention, the first layer is never in direct contact with the second layer and the container further comprises a junction element of ceramic material positioned at the edge portion of the containment wall for an indirect connection between the first and the second layer.

In this way, the container can be considered as an assembly of two recipients of roughly the same shape coupled to one another, for example one inserted inside the other. The junction element therefore serves to connect the two separate recipients and form a single container. In the case wherein the container has the shape of a glass, the two recipients representing the inner layer and the outer layer of the containment wall would have the form of two glasses, so that the external glass should be able to totally contain the internal glass without however being in contact therewith, so as to form a gap between the surfaces of the two recipients. The junction element can thus assume the shape of a ring which is interposed in the space present between the upper edges of the two glasses.

In particular, in an embodiment of the invention, the ceramic material of the junction element comprises a spongy reticulated material or nanospheres made of a hard feldspathic porcelain, defining a density of the material which is lower than the density of the first and second layer (10, 20).

Since a low density in a material determines a reduction in heat conduction, the presence of a junction element positioned on the edge portion of the containment wall having a lower density than the rest of the container is such that the substance contained inside the container maintains a constant temperature for a longer time even in the absence of an insulating cap or cover.

In an additional or alternative embodiment of the present invention, the containment wall comprises at least a region having low heat conduction at the edge portion thereof, wherein the ceramic material of the first and second layer in said region comprises a spongy reticulated structure or nanospheres made of a hard feldspathic porcelain defining a density of the material which is lower than the density of the material outside said region (60).

In a like way to what is described for the junction element with a low density, the low heat conduction region can further increase the effects of maintaining the heat inside the container, preventing transfer of the heat from and towards the inside of the container.

This can be realised during the firing step of the two layers, by modifying the material at a determined moment, for example inside the mould.

In an embodiment of the present invention, the closing means are held in position by a pressure change exerted on said closing means by the vacuum created inside the gap.

In this way it is possible to hermetically close the hole with no use of adhesive substances. A process of this type can be realised automatically by means of a suitable robotic system even during the steps of an assembly line acting inside a vacuum system. The region of the containment wall having the hole can advantageously be realised as a cavity or recess so that the closing means adapt perfectly to the shape of said cavity. In this way, once the closing means have been applied, the surface of the containment wall will be continuous without the presence of steps or recesses. The closing means can assume the form of a small rectangular or circular plate, or a plate of any other shape having a thickness of a few millimetres.

The hermetic closing kit according to the present invention comprises a container as described in the foregoing and a closing element to be positioned at the edge portion of the containment wall of the container so as to close the opening of the container.

In a like way, to the containment wall of the container, the closing element is constituted by two layers of ceramic material or porcelain separate from one another and defining a gap inside which the vacuum is created. Further, the closing element is constituted by at least a sealing element made of a polymeric material coupled to the closing element, wherein, in a closed configuration, the sealing element is in direct contact with the containment wall of the container for hermetically closing the opening.

The sealing element can be made of soft polymeric materials such as silicone.

The closure can also be achieved with direct contact between the ceramic and/or the porcelain materials, without the polymeric layer, with the designing of a perfect fit.

The closing element can be a separate element from the container or can be connected thereto for example by means of a hinge system. In the latter case, the closing element can function as a hatch or door, easy to open and close by means of an engaging and disengaging mechanism.

In this way, it is possible to obtain a perfectly insulating container for maintaining the temperature of the contained substance even for very long times.

The method according to the present invention for realising a thermal insulating container as described in the foregoing, comprises steps of realising a first layer, or outer layer, of ceramic material with a firing process at a temperature T₁, said first layer defining the outer continuous containment wall of the container and realising a second layer, or inner layer, of ceramic material with a firing process at a temperature T₂, equal to T₁, said second layer defining the inner continuous containment wall of the container and being separated from the first layer so as to form a gap region.

Further, the method according to the present invention comprises the step of creating the vacuum inside the gap formed between the first and the second layer.

In particular, the creation of the vacuum takes place by extracting the air through a hole present on the outer layer, in which the hole is previously used for the exit of the air during the firing step of the ceramic material. Maintaining the vacuum inside the gap is achieved by use of closing means which hermetically close the hole once the vacuum has been created.

The description in relation to the characteristics of the container can also be considered valid in regard to the method of realisation.

In particular, the firing temperatures T₁ and T₂, regarding the realisation of the first and second layer, are comprised between 1200° C. and 1350° C., in the case of porcelain. The firing times are instead preparation cycles of the material which vary from a few hours to 24 hours for a hard feldspathic porcelain cycle.

In an embodiment of the invention, the first layer and the second layer are made contemporaneously with a single firing process, in which the first layer forms a continuous body with the second layer and is in direct contact with the second layer at least at the edge portion of the containment wall.

In an alternative embodiment, before creating the vacuum inside the gap, the method comprises the step of realising a junction element of ceramic material by a firing process at a temperature T₃ and hermetically fixing said junction element at the edge portion of the containment wall for an indirect connection between the first and the second layer.

In particular, the step of hermetically fixing the junction element to the containment wall takes place by a firing process at a temperature T₄, much lower than T₁, or through a gluing or welding process.

Specifically, the temperature T₄ can assume a value of even lower than 100° C.

The firing of the junction element can advantageously be realised inside an induction furnace so as to delimit the firing to the region of the junction element, thus avoiding a re-firing of the rest of the container. This is extremely useful in a case in which the container is provided with areas at different densities which, with a re-firing process, might spread inside the containment wall. Likewise, this is extremely advantageous if inside the gap it is necessary to apply elements (such as electronic components) which might not withstand a firing process at high temperatures.

In an embodiment of the present invention, the closing means are held in position by a pressure change exerted on said closing means by the vacuum created inside the gap.

The value of the pressure in the gap passes from ambient pressure 0.00001 mbar, up to absolute vacuum.

It is stressed that similar results can be obtained also using different materials from ceramic materials, or from porcelain, as regards the manufacturing of the first and second layer defining the containment wall. These and other aspects of the present invention will become more apparent in light of the following description of some preferred embodiments described herein below.

FIG. 1 shows a schematic view of a container according to the present invention;

FIGS. 2a, 2b are a schematic representation of a container in which the first layer forms a continuous body with the second layer (2 a) and in which the second layer is separated from the first layer (2 b);

FIG. 3 is a schematic representation of the container according to an embodiment of the present invention;

FIG. 4 is a schematic view of a hermetic closing kit according to the present invention;

and

FIG. 5 is a flow chart of the steps of the method for realising the container.

FIG. 1 shows the thermal insulating container 1 having a glass shape. The container 1 comprises a continuous containment wall 3 which extends in a single body and defines an inner containment region 8 with an opening. FIG. 1 in particular shows how the opening 4 is present on the upper portion of the container 1 opposite the base thereof.

The containment wall 3 comprises an edge portion 6 in proximity of the opening 4 and is constituted by an outer layer 10 and an inner layer 20. These two layers respectively determine an outer wall in contact with the external environment (outer layer 10) and an inner wall facing towards the inner containment region 8 (inner layer 20). The two layers are separate from one another so as to form a gap 30. A vacuum is created inside the gap.

The outer layer 10 comprises a hole 22 positioned on the base of the container 1 for air passage and closing means 40 for hermetically closing the hole 22 once the vacuum has been created inside the gap 30.

Both the first and the second layer 10, 20 are made of hard feldspathic porcelain. In this way, a container 1 can be obtained that is highly resistant and which can function effectively as thermal insulation. In fact, the hardness of the porcelain guarantees excellent resistance of the walls, even in a presence of a vacuum inside the gap. Further, the tried and tested production methods of ceramic material and porcelain guarantee an easy production of containers of any shape and size.

FIGS. 2a and 2b show two different and alternative embodiments of the container 1 according to the present invention.

FIG. 2a illustrates the configuration in which the first layer 10 forms a continuous body with the second layer 20. In particular, the first layer 10 is in direct contact with the second layer 20 at least at the edge portion 6 of the containment wall 3.

FIG. 2b instead shows the configuration in which the outer layer 10 and the inner layer 20 are not in direct contact. To make a connection between the two layers, a junction element 50 of ceramic material is provided, positioned at the edge portion 6 of the containment wall 3. Specifically, the junction element 50 has a ring shape which inserts in and adapts to the space present between the inner layer 20 and the outer layer 10.

The junction element 50 is fixable to the edge 6 of the container 1 by means of a low-temperature firing process in an induction furnace.

FIG. 3 shows a container 1, in which the containment wall 3 comprises a region 60 having low heat conduction at the edge portion 6 thereof. In particular, the ceramic material of the first and the second layer 10, 20 in this region 60 has a lower density than the material in the rest of the containment wall 3 outside the region 60.

FIG. 4 shows a container 1 provided with a closing element or cover 70. The cover is realised with two layers 72, 74 made of a ceramic material, separated from one another so as to define a gap 30′. A vacuum is achieved inside the gap 30′ so as to prevent heat conduction through the opening 4. With the aim of preventing dispersion of heat, the closing element 70 is provided with polymeric material, such as silicone, at the edges thereof.

Lastly, FIG. 5 is a flow chart describing the method 100 for realising the container 1.

The method 100 is essentially characterised in the realising of a first layer 102, 106; 110, or outer layer, of ceramic material with a firing process at a temperature T₁, realising a second layer 102, 106; 112, or inner layer, of ceramic material with a firing process at a temperature T₂, equal to T₁ and creating the vacuum 104 inside the gap 30 formed between the two layers 10, 20.

As regards the realising of the two layers, this can take place in a single step with a single firing process 106 or alternatively separately 110, 112, with two distinct firing processes. In this second case, before creating the vacuum inside the gap 30, following the realising of the two layers 10, 20, a junction element 114 is realised, made of a ceramic material, with a firing process at a temperature T₃ (equal to T₁) and the junction element is hermetically fixed 116 at the edge portion 6 of the containment wall 3 for an indirect connection between the first and the second layer 10, 20. Concerning the creation of the vacuum 104, this is created by extracting the air 118 through a hole 22 present on the outer layer, in which the hole 22 is previously used for the exit of the air during the firing step of the ceramic material. Maintaining the vacuum 120 inside the gap 30 is done by use of closing means 40 which hermetically close the hole 22 once the vacuum has been created.

A person skilled in the art can introduce numerous further modifications and variations to the container, the kit and the method described in the foregoing, for the purpose of satisfying further and contingent requirements, all comprised within the scope of protection of the present invention as defined in the appended claims. 

1. A thermal insulating container for containing one or more substances and maintaining the substances at a determined temperature, the container comprising a continuous containment wall which extends in a single body and defines an inner containment region with an opening, the containment wall having an edge portion in proximity of the opening, wherein the containment wall is constituted by: a first layer, or outer layer, of ceramic material, and a second layer, or inner layer, facing towards the inner containment region of ceramic material and separated from the first layer so as to form a gap region inside which the vacuum is created, in which the outer layer comprises at least a hole for exit of the air during the step of firing the ceramic material and for extraction of the air and creation of the vacuum inside the gap following said firing and wherein the container further comprises closing means for hermetically closing the hole once the vacuum has been created.
 2. The container according to claim 1, wherein the ceramic material is hard feldspathic porcelain.
 3. The container according to claim 1, wherein the ceramic material of the first and second layer prevalently comprises feldspar, quartzes and kaolin and variable densities of material due to structures similar to sponges and/or nanospheres.
 4. The container according to claim 1, wherein the first layer forms a continuous body with the second layer and is in direct contact with the second layer at least at the edge portion of the containment wall.
 5. The container according to claim 1, wherein the first layer is never in direct contact with the second layer and the container further comprises a junction element of ceramic material positioned at the edge portion of the containment wall for an indirect connection between the first and the second layer.
 6. The container according to claim 5, wherein ceramic material of the junction element comprises a spongy reticulated material or nanospheres made of a hard feldspathic porcelain defining a density of the material which is lower than the density of the first and second layer.
 7. The container according to claim 1, wherein the containment wall comprises at least a region having low heat conduction at the edge portion, wherein the ceramic material of the first and second layer in said region comprises a spongy reticulated material or nanospheres made of a hard feldspathic porcelain defining a density of the material which is lower than the density of the material outside said region.
 8. The container according to claim 1, wherein the closing means are kept in position by a pressure variation exerted on said closing means by the vacuum created inside the gap.
 9. A hermetic closing kit comprising a container according to claim 1 and a closing element to be positioned at the edge portion of the containment wall of the container so as to close the opening of said container, the closing element being constituted by two layers of ceramic material separate from one another and defining a gap inside which the vacuum is created and at least a sealing element made of a polymeric material coupled to the closing element, wherein, in a closed configuration, the sealing element is in direct contact with the containment wall of the container for hermetically closing the opening.
 10. A method for realising a thermal insulating container according to claim 1, the method comprising following steps: realising a first layer, or outer layer, of ceramic material with a firing process at a temperature T₁, said first layer defining the outer continuous containment wall of the container, realising a second layer, or inner layer, of ceramic material with a firing process at a temperature T₂, equal to T₁, said second layer defining the inner continuous containment wall of the container and being separated from the first layer so as to form a gap region, and create the vacuum inside the gap formed between the first and the second layer, wherein the creation of the vacuum takes place by extracting the air through a hole present on the outer layer, said hole being previously used for exit of the air during the firing step of the ceramic material and maintaining the vacuum inside the gap is done by use of closing means which hermetically close the hole once the vacuum has been created.
 11. The method according to claim 10, wherein the first layer and the second layer are made contemporaneously with a single firing process, the first layer forming a continuous body with the second layer and being in direct contact with the second layer at least at the edge portion of the containment wall.
 12. The method according to claim 10, further comprising, before creating the vacuum inside the gap, a step of realising a junction element of ceramic material by a firing process at a temperature T₃ and hermetically fixing said junction element at the edge portion of the containment wall for an indirect connection between the first and the second layer.
 13. The method according to claim 12, wherein the step of hermetically fixing the junction element to the containment wall takes place by a firing process at a temperature T₄, much lower than T₁, or by means of a gluing or welding process.
 14. The method according to claim 1, wherein the closing means are held in position by a pressure change exerted on said closing means by the vacuum created inside the gap.
 15. The method according to claim 1, wherein the hermetic closing of the hole using a robotic system guarantees a null or very nearly null value of the pressure inside the gap. 